This invention relates to a method of processing a sample including an etching step, and to an apparatus for carrying out such a method, and more particularly to a processing method and apparatus which is suitable for processing a sample in the manufacture of a semiconductor device or other device including miniaturized components.
A sample such as a semiconductor device substrate is etched by a chemical solution or by plasma, for example. Sufficient care must be paid to corrosion protection of the sample after etching processing.
A corrosion-proofing technique after etching is disclosed, for example, in U.S. Pat. No. 4,487,678. This technique subjects a resist film, after etching by plasma inside an etching chamber, to removal in a second plasma processing chamber connected to the etching chamber. The second plasma treatment removes chlorine compounds which are corrosive components remaining in the resist film or on the etched surface. It is also known to heat the sample after etching to at least 200° C. in order to promote evaporation of chlorides that are residual corrosive components. Japanese Laid-Open Patent Publication No. JP-A-61-133388 discloses a method in which a sample after plasma etching is transferred to a heat-treating chamber in which hot air is blown on it to remove corrosive compounds. Thereafter the sample is washed with water and dried.
The present applicants have found that these aforementioned techniques involve the problem that sufficient corrosion-proofing performance cannot be obtained, at least for certain kinds of samples.
For instance, the techniques described above are believed effective in some cases for corrosion-proofing of a single metallic film such as an aluminum (Al) wiring film. However, they fail to provide a sufficient corrosion-proofing effect after etching of a sample having metals having mutually different ionization tendencies such as films of Al, Cu, W, Ti, Mo, etc. and their alloys or laminates, e.g., as a laminate wiring structure.
With the remarkable progress in miniaturization in recent years, wiring films have been more and more miniaturized, and an Al—Cu—Si alloy film having a few percent of Cu content in place of the conventional Al—Si alloy film and a laminate structure of the Al—Cu—Si alloy film and a refractory metal film such as titanium tungsten (TiW), titanium nitride (TiN) and molybdenum silicon (MoSi) film for reducing contact resistance have gained wide application as a wiring film in order to prevent breakage due to electromigration and stress migration. In such a wiring film structure, ionization tendencies of Al and Cu, W, Ti, Mo or the like are different so that a battery action develops due to water acting as an electrolyte, and corrosion of the wiring film is accelerated by so-called “electrolytic corrosion”. Even if corrosive materials generated by etching are removed by utilizing plasma at a high temperature of 200° C. or above, corrosion occurs due to the effect of moisture on remaining corrosive compounds within some minutes or several hours after the sample is withdrawn into the atmosphere.
As a countermeasure of the above “electrolytic corrosion” problem, there has been proposed, as disclosed in Japanese Laid-Open Publication No. Hei 2-2242233, a sample processing apparatus comprising means for processing a sample (e.g., etching processing the sample), means for post-processing a processed sample, the post-processing means utilizing a plasma, means for wet-processing a processed sample processed through the plasma post-processing means, and means for dry-processing a processed sample which has been processed through the wet-processing means. Corrosion of the sample after the etching processing, irrespective of the kind of the sample, can be prevented effectively utilizing this sample processing apparatus.
However, since the sample processing apparatus shown in the above-discussed Japanese Laid-Open Publication No. Hei 2-2242233 comprises a single means for wet-processing the sample processed through the plasma post-processing means, the through-put is limited; moreover, when the wet-processing time is lengthened, such that the corrosion-preventing effect is improved, a further problem is caused that the through-put is even further lowered.